The invention relates to a monitoring device for protected areas which are to be monitored, for example of machines or machinery installations, of which the access doors or openings are provided with a safety-switch device in order to prevent unauthorized access into hazardous areas with operating machinery such as robots or the like.
From German Laid-Open Patent Application DE 19711 588 A1 a monitoring device is known, in which there is provided a conventional safety switch which can be actuated by a key-like actuator which, for its part, is fastened on a door or the like. The door itself can be opened and closed via a separate handle. In this case, the actuator is merely screwed to the door and can thus also be removed in a straightforward manner. However, this results in it being possible for the safety switch to be actuated by the detached actuator, with the door open, and thus for the safety switch to be outsmarted.
Moreover, U.S. Continuation In Part patent application Ser. No. 09/317,338 dated May 24, 1999 (EP 0 825 628 A), incorporated herein by reference, discloses a monitoring device in which there is provided at least one safety switch which can be actuated via a key-like actuator. In this case, the actuator, with the door in the closed state, can be displaced longitudinally by means of a door handle and a toothed-ring segment, which is in engagement with a rack section of the actuator, into the housing of the safety switch in order to actuate the latter mechanically.
It is an object of the invention to provide a monitoring device of which the safety switch, in addition to allowing the contactless release and mechanical locking thereof, allows actuation, in practice, only when the movable element is closed.
Thus, according to the invention there is provided a monitoring device for a protected area of a machinery installation, the area being accessible via at least one access opening which can be closed off via an element movable between an open position and a closed position and is in the form of a door, shutter or the like; comprising a safety switch provided with a housing, connected to an evaluation device and arranged adjacent to the movable element, said safety switch being further provided with a read head for reading, in the closed position of the movable element, data stored in a coded release mechanism located on the movable element; said movable element being provided with an actuator which, in its end position in the housing, locks the movable element in its closed position and which bears the release mechanism, while the housing has a receiving space for the actuator and receives the read head in a position in which, in the end position of the actuator in the housing, it is located adjacent to the release mechanism, wherein the actuator is movable in relation to the movable element by coupling to a handle provided on the movable element.
Further objects, advantages and embodiments of the invention will become apparent from the following description and the claims.